The South African government is considering blocking the Dalai Lama from attending the 80th birthday of fellow Nobel peace laureate Desmond Tutu so as not to offend China, according to opposition politicians.

Tutu has invited the Tibetan spiritual leader to give a lecture as part of his birthday celebrations in Cape Town on 8 October. Officials from the former archbishop's office started the visa application process in June, but have yet to get approval for the Dalai Lama's visit and fear it may not come.

The Dalai Lama was refused entry to South Africa in 2009, a move that conflicted with the country's progressive human rights policies and was widely criticised at home.

"We've sent letters, following up on a daily basis with phone calls and still are in a situation where there is no response and it's getting us much more anxious," said Nomfundo Wazala, chief executive of the Desmond Tutu Peace Centre. "We have been patient, but we really feel at this point in time we deserve an answer." South African officials have denied dragging their heels.

The Dalai Lama, 76, fled Tibet in 1959 during a failed uprising against China and lives in exile in India. Revered by his followers as the 14th reincarnation of the Buddha Avalokiteshvara, he is reviled by the Chinese government as a separatist. Beijing repeatedly warns the leaders of other nations against meeting him.

The Dalai Lama stepped down from political life earlier this year and is not due to meet any senior South African government officials during his eight-day trip. As part of Tutu's birthday celebrations from 6 to 8 October, he is due to deliver a speech titled: "Peace and compassion as catalyst for change".

The Dalai Lama visited South Africa in 1996, meeting the then president, Nelson Mandela, but he was prevented from attending a Nobel laureates' conference in South Africa two years ago when the government said his visit would distract from preparations for the 2010 World Cup. At the time, Tutu called the decision "disgraceful" and accused the authorities of bowing to pressure from China, South Africa's biggest trade partner.

South Africa's main opposition party, the Democratic Alliance, said on Tuesday that "our own history and values", rather than Chinese sensitivities, should be the determining factor when considering the Dalai Lama's application.

South Africa is a member of Brics, the international organisation of leading emerging market countries, along with Brazil, Russia, India and China. "As a Brics partner with the Chinese, we must view our relationship with them as equals, not subordinates," said Stevens Mokgalapa, the Democratic Alliance party's deputy spokesman on international relations and co-operation. "We call on the government to show our foreign policy is 'made in South Africa', not 'made in China'."

At a daily press briefing in Beijing, Chinese foreign ministry spokesman Hong Lei would not reveal whether there had been talks with South Africa over the visa, but said that "China's position of opposing the Dalai Lama visiting any country with ties to China is clear and consistent".The Chinese government reacted angrily this month when the Dalai Lama met the Mexican president, Felipe Calderón, saying it had "harmed Chinese-Mexican relations". Beijing was also critical of US president Barack Obama after he received the Tibetan spiritual leader at the White House in July.

South Africa's foreign affairs department denied there had been any pressure from China, and said a complete visa application had only been received on 20 September. This was denied by the Dalai Lama's representatives, as well as Tutu's peace centre, which said three letters to the South African government, as well as a personal plea from Tutu to senior officials, had not yielded any results.

In a statement, Tutu's office said the delay in approving the visa was a "major stumbling block" for the organisers of the birthday celebrations.

Besides delivering the inaugural Desmond Tutu International Peace Lecture, the Dalai Lama is also due to deliver a speech at Stellenbosch University and to receive the Mahatma Gandhi award for reconciliation and peace from the Mahatma Gandhi Trust in Durban. South Africa's newspapers were critical of the delay to welcoming the Dalai Lama to the country.

In an editorial last week, the Cape Times said "the government's squeamishness has nothing to do with him [the Dalai Lama] and everything to do with not wanting to annoy China, the new economic powerhouse and a potential source of growth for South Africa's flagging economy."